Objective: This study aimed to evaluate the aetiology, spectrum, course and outcomes of neonates with arrhythmias observed in a tertiary neonatal intensive care unit from 2007 to 2012. Methods: Neonates with rhythm problems were included. The results of electrocardiography (ECG), Holter ECG, echocardiography and biochemical analysis were evaluated. The long-term results of follow up were reviewed. Results: Forty-five patients were male (68%) and 21 (32%) were female. Fifty-five patients (83.3%) were term, 11 (16.6%) were preterm, and 34% were diagnosed in the prenatal period. Twenty cases (30.3%) had congenital heart disease. Twenty-three patients (34.8%) were diagnosed during the foetal period. The most common arrhythmias were supraventricular ectopic beats and supraventricular tachycardia (SVT) at 39.3 and 22.7%, respectively. SVT recurred in five patients after the neonatal period. Conclusion: Supraventricular ectopic beats and SVT were the most common arrhythmias during the neonatal period. Although the prognosis of arrhythmias in the neonatal period is relatively good, regular monitoring is required.